Contrary to time consuming and only indirect bioanalytical methods, such as ELISA, affinity biosensors are capable of detecting target biomarkers in real time. However, the sensors have not been applied to medical diagnostics yet due to the nonspecific protein deposition. A goal of the work is to develop sensitive layers which would allow the sensors to detect biomarkers in complex biological medium (eg. blood plasma, serum, saliva). The work will include application of new methods, which are currently developed in IMC, to coating optical sensors with antifouling polymer brushes and successive immobilization of bioreceptors for detection of specific biomarkers.